Conventionally, there is a technology called “streaming” for distributing packet data like images and speech from a media server on the Internet and receiving and playing back the data at a mobile station apparatus. According to this streaming technology, through a radio network connected to the Internet and a base station apparatus connected to the radio network, data such as moving images distributed from a media server is received by a mobile station apparatus from the base station apparatus and the moving images, etc., are played back. The mobile station apparatus that has received packet data such as moving images plays back the data such as moving images received from the media server.
In such a streaming technology, a phenomenon called “jitter” occurs in which a delay in data reception increases or decreases according to the network condition. When a delay occurs in data reception due to jitter, the data reception rate becomes lower than the data play back rate. In this case, if the received data is continued to be played back, it comes to a point at which there is no more data to be played back and the play back is no longer possible, and therefore the mobile station apparatus is provided with a buffer, the received data is temporarily stored in this buffer, the data is read from the buffer and played back. In this way, even if some delay occurs in received data, the data stored in the buffer is used for playback and it is there by possible to prevent play back of data from being stopped due to the delay of the received data. Therefore, when playback of data is started for the first time, an operation called “initial buffering” is performed first whereby a predetermined amount of data is stored in the buffer before the data is played back.
However, in the case of the conventional radio apparatus, the rate at which data is stored in the buffer before data play back is started is the same as the rate at which the data is stored in the buffer after the data play back is started, and therefore there is a problem that it takes time to store data in the buffer and it takes an excessive time after requesting the server to send data until the data is played back. Furthermore, it is also possible to request the server so as to increase the data transmission rate, but when the transmission rate is requested to be increased, the buffer becomes empty when a delay occurs in the received data due to congestion, etc., of the network, running short of data to be played back, making it impossible to play back the data.